Forest Planting Genetically Altered Squirrels, Research Shows
Copyright 2001 The Press Association
September 21, 2001
By John von Radowitz, Science Correspondent, PA News
Red squirrels in Cumbria have been genetically altered by the planting of a large conifer forest, scientists have said.
The Kielder forest provided a bridge between disconnected forest fragments, allowing an influx of new genes carried by "foreign" squirrels.
As a result, the genetic composition of Cumbria's red squirrel population changed completely in the 1980s. The researchers, led by Marie Hale from the University of Newcastle, said last night that the findings had implications for conservation management.
They suggested that human-made alterations to the connectivity of a landscape could result in long distance genetic changes in animal and plant populations.
The scientists studied genetic markers in 102 dried red-squirrel skins collected in northern England and southern Scotland.
According to their genetic hallmarks, they were assigned to northern, eastern or western forest fragments.
The study found that Cumbrian samples collected after the 1980s were significantly different from those pre-dating the 1980s.
The change coincided with the growth of the Kielder forest, which was planted in the 1920s and by the 1960s had started to create a link between northern and western squirrel regions.
Red squirrels, still relatively abundant in the north of England and Scottish borders, live in isolated patches of forest which would normally prevent genetic mixing between populations.
However, the red squirrel is known to use woodland "stepping stones" to jump from one habitat to another.
The appearance of the Kielder forest prompted a north to west squirrel migration which changed the Cumbrian population.
Pre-1980, eight out of nine Cumbrian squirrels belonged to the "western" group. After 1980, 76% of Cumbrian squirrels were "northern".
The findings were reported in the journal Science.
The researchers wrote: "The northern genes have leapfrogged through hundreds of forest fragments in a period of 20 years, demonstrating the use of stepping stone patches of forest by red squirrels."